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Biomedical subjects

A Paquet

Publications and source records attributed to A Paquet.

At least 19 recordsLinked to original sources
PubMed1998

Influence of carbohydrate status on immune responses before and after endurance exercise.

To determine the effect of carbohydrate (CHO) status on immune responses after long-duration exercise, on two occasions, 10 men completed a glycogen-depleting bout of cycle ergometry followed by 48 h of either a high-CHO diet (HiCHO; 8.0 g CHO/kg) or a low-CHO diet (LoCHO; 0.5 g CHO/kg). After the 48 h, subjects completed a 60-min ride at 75% maximal O2 uptake (EX). Blood samples were taken predepletion, pre-EX, post-EX, and 2 and 24 h post-EX and were assayed for leukocyte number and function, glucose, glutamine, and cortisol. The glucose responses were significantly higher in the HiCHO (4.62 +/- 0.26 mM) vs. the LoCHO (3.19 +/- 0.15 mM) condition post-EX, and glutamine was significantly higher in the HiCHO (0.472 +/- 0.036 mM) vs. the LoCHO (0.410 +/- 0.025 mM) condition throughout. Cortisol levels were significantly greater in the LoCHO (587 +/- 50 nM) vs. the HiCHO (515 +/- 62 nM) condition throughout the trial. Lymphocyte proliferation (phytohemagglutinin) was significantly depressed after exercise. However, there was no difference between conditions, and the depression was not correlated with elevations in cortisol. Circulating numbers of leukocytes, neutrophils, lymphocytes, and lymphocyte subsets were significantly greater in the LoCHO vs. the HiCHO condition at the post-EX and 2 h post-EX time points. These data indicate that the exercise and diet manipulation altered the number of circulating leukocytes but did not affect the decrease in lymphocyte proliferation that occurred after exercise.

Adult↗
PubMed1997

Synthesis of phosphotyrosine-containing peptides using bis-(2,2,2-trichloro)ethyl groups for phosphate protection.

Suitability of bis-(2,2,2-trichloro)ethyl (Tc) groups for protection of phosphate moiety in Boc-mode synthesis of phosphotyrosine peptides is demonstrated Boc-Tyr(PO3Tc2)-OH and Fmoc-Tyr(PO3Tc2)-OH were prepared by acylating H-Tyr(PO3Tc2)-OH with (Boc)2O and Fmoc-ONSu, respectively. Phosphorus introduction was achieved by phosphorylating Boc-Tyr-OBzl with Tc phosphochloride. The Tc-phosphorus protector was found to be incompatible with the Fmoc group because the conditions of Fmoc removal (piperidine treatment) caused dephosphorylation. Complete NMR spectral assignments in the described compounds is presented. (Contribution No. 2398 from the Centre for Food and Animal Research).

Hydrocarbons, Chlorinated↗
PubMed1995

Measurement of tumor necrosis factor activity by flow cytometry.

Tumor necrosis factor-alpha (TNF-alpha) is a monokine of 17 kDa produced by activated macrophages and various cells involved in the immune system. We propose a new method for the measurement of TNF activity using flow cytometry. After an incubation with TNF, L929 cells were harvested and treated with a calcein-AM and ethidium homodimer-1 solution. Nonfluorescent calcein-AM is hydrolyzed by intracellular esterases to yield fluorescent calcein. The ethidium homodimer-1 is a high-affinity red fluorescent DNA dye that is internalized only through altered cell membranes. A very good correlation was observed between the calcein fluorescence intensity and the number of viable cells as well as the ethidium fluorescence and the number of cells with altered membranes. The assay is sensitive, inexpensive, and correlates with the already reported crystal violet assay while measuring membrane alteration by TNF. It allows the simultaneous measurement of total living and dead cells. There is no interference with culture medium components. This method is rapid and may be used for routine measurement of TNF activity.

Animals↗
PubMed1995

Improved fluorescent bioassay for the detection of tumor necrosis factor activity.

Tumor necrosis factor alpha (TNF-alpha) is a monokine of 17 kDa produced by activated macrophages and various cells involved in the immune system. We propose a new method for the measurement of TNF activity on mouse L929 fibroblast cells. After an incubation with TNF, the cells were stained with a solution of ethidium homodimer-1, a high-affinity red fluorescent DNA dye that is internalized only through altered cell membranes. The assay is sensitive, inexpensive and correlates with the already reported TNF assays while measuring the membrane alteration by TNF and not the cell detachment. It requires no rinsing before dye addition which may cause cell loss; there is no interference with culture medium components since the assay is performed in PBS. This method is more rapid and precise for routine measurement of TNF activity.

Animals↗
PubMed1994

Rapid purification method for human recombinant tumor necrosis factor alpha.

Human recombinant tumor necrosis factor alpha was purified in a single step to about 95% purity from Escherichia coli lysate by chromatography on hydroxyapatite. The last traces of contaminants were removed by fast protein liquid chromatography on a Mono Q column. The final product was found to be pure by gel electrophoresis with silver staining. A molecular mass of approximately 17,000 and a specific activity of 4.3 x 10(6) U/mg after a single purification step were found.

Amino Acids↗
PubMed1994

Comparative metabolism of deltamethrin and 3-phenoxybenzoic acid in chickens.

A comparative metabolism of [benzyl 14C]deltamethrin and 3-phenoxybenzoic acid (3-PBacid) was carried out in chickens. The effect of oral and intravenous route of administration was also investigated. There was no difference in the metabolic profile of [14C] portion of deltamethrin and 3-PBacid. Similarly, no effect on the nature of metabolites excreted due to mode of administration was observed. Biotransformation of orally dosed compounds did not occur in the intestine, but were absorbed and metabolized by liver (deltamethrin) and kidney (3-PBacid). 3-PBacid, the primary metabolite of deltamethrin, was readily metabolized into 3-hydroxy benzoic acid (3-HO-Bacid) which is conjugated with a variety of endogenous substances to form sulphates, glucuronides, butyl ester and peptides. HPLC and LC-Ms methods were used to ascertain the structures of metabolites.

Administration, Oral↗
PubMed1992

Further studies on the use of 2,2,2-trichloroethyl groups for phosphate protection in phosphoserine peptide synthesis.

Boc-Ser(PO3Tc2)-OH, Z-Ser(PO3Tc2)-OH and Fmoc-Ser(PO3Tc2)-OH, derivatives useful for peptide synthesis, have been obtained in high yields by acylation of H-Ser(PO3Tc2)-OH.CF3COOH. The latter was obtained from Boc- or Z-Ser(PO3Tc2)-OBzl by simultaneous removal of the amino- and carboxy-protecting groups by Pd-catalyzed hydrogenolysis in acetic acid-trifluoroacetic acid solution. Removal of the Tc-protecting group was efficiently achieved by hydrogenolysis in aqueous ethanol.

Amino Acid Sequence↗
PubMed1992

Immunomodulating activities of Corynebacterium xerosis cell-wall fractions.

Corynebacterium xerosis cell-wall fractions were studied by electron microscopy and analysed for immunomodulating activity. Dramatic splenomegaly occurred following the injection of whole cells or a purified cell-wall fraction (PF), but not with a further purified peptidoglycan (PEP) fraction. Both PF and PEP acted as B-cell mitogens and had adjuvant capabilities comparable to commercial adjuvants. Only the PF fraction enhanced peritoneal natural killer cell (NK) activity, paralleling the splenomegaly response. When spleens from mice injected with PF or PEP were analysed for their abilities to respond to mitogens and for the presence of suppressor cells, reduced mitogenic responses occurred only in PF-injected mice during the peak of splenomegaly. Spleens from both PF- and PEP-injected mice contained suppressor cell activity which peaked 2 weeks post-injection. This activity was primarily directed at B-cell responses to lipopolysaccharide (LPS). C. xerosis cell-wall fractions thus offer great potential as a new immunomodulator.

Adjuvants, Immunologic↗
PubMed1990

Standing views to differentiate gallbladder or bile leak from duodenal activity on cholescintigrams.

Confusing a gallbladder or bile leak with duodenal activity is a common source of error in the interpretation of cholescintigrams. Techniques such as supplementary oblique views, delayed views, the "water test," dynamic display and combined cholescintigraphy and ultrasound have been used with varying degrees of success. As illustrated in two cases, supplementary standing views provide a simple alternative method to differentiate gallbladder from small bowel activity.

Adolescent↗
PubMed1990

Synthesis of oligophosphoseryl sequences occurring in casein. Identification of beta-elimination during phosphorylation.

The protected oligophosphoseryl peptides from bovine caseins, Z-Xxx-(Ser[PO(OPh)2])3-Glu(OBzl)-OBzl for Xxx = Ile, Val, Gly, Leu and Ph = phenyl, were synthesized in high yields by stepwise lengthening using Boc-Ser[PO(OPh)2]-OH as acylating carboxyl component and N-ethyl-N'-(3-dimethylaminopropyl)-carbodiimide hydrochloride as coupling reagent. The hydrogenolytic deprotection (PtO2) was carried out with the valine derivative and with the tetrapeptide Ser[PO(OPh)2]3-Glu(OBz)-OBzl. Phosphorylation of oligoseryl peptides failed to give the expected products. Large scale phosphorylation of protected serine was carried out in the presence of triethylamine using absolute ether as a solvent. 2,2,2-Trichloroethyl group (Tc) was shown to be a useful phosphorus protecting moiety in phosphopeptide synthesis: Boc-Ser[PO(OTc)2]-OBzl, Z-Ser[PO(OTc)2]-OBzl and Boc-Glu(OBzl)-Ser[PO(OTc)2]-OBzl were synthesized in high yields using bis-(2,2,2-trichloroethyl) phosphochloridate.

Amino Acid Sequence↗
PubMed1987

Some N-acyl-D-amino acid derivatives having antibotulinal properties.

Several N-acyl derivatives of D-tryptophan, D-alanine, D-methionine, D-valine, and D-aspartic acid were synthesized in high yields using the succinimidyl ester method and examined for their antibotulinal properties. In conjunction with 60 ppm of sodium nitrite, sorbyl-D-tryptophan, sorbyl-D-alanine, myristoyl-D-aspartic acid, and glycyl-D-alanine were highly inhibitory. In the absence of sodium nitrite, the N-acyl derivatives of the D-amino acids were not inhibitory. On its own, 60 ppm of sodium nitrite was only slightly inhibitory. Sorbyl-L-tryptophan and sorbyl-L-alanine had no effect in the presence or absence of 60 ppm of sodium nitrite.

Amino Acids↗
PubMed1986

Immunopotentiating activities of cell walls, peptidoglycans, and teichoic acids from two strains of Listeria monocytogenes.

Crude cell wall (CCW), enzyme purified wall (PF), peptidoglycans (PEP), and teichoic acid fractions from two strains of Listeria monocytogenes (EGD and a human isolate) were analyzed by electron microscopy, chemical analyses, and various immunological assays. Electron microscopy and chemical analyses revealed that both strains were quite similar. The CCW, PF, and PEP fractions were mitogenic for mouse lymphocytes, could activate macrophages in vivo but not in vitro, and stimulated nonspecific immunity in vivo to Candida albicans. The PF and PEP fractions but not the CCW induced migration inhibition factor production. The CCW and PEP fractions were tested and found to elevate natural killer activity in vivo. Teichoic acid fractions had no activity in the above assays. Since most of the immunological activities were retained in the PEP fraction, we examined this fraction to determine the kinetics of the mitogenic response and the nature of the responding cell population. The peak mitogenic response occurred on day 2 over a 6-day period. This response was not enriched in T-cell-enriched populations but followed the pattern of LPS in B-cell-enriched populations.

Adjuvants, Immunologic↗
PubMed1986

Polysorbate 80 and E-Ferol toxicity.

The relatively recent introduction and use of an intravenous form of a vitamin E preparation (E-Ferol) has been associated with the development of an unusual syndrome and fatalities among low birth weight (less than 1,500 g), premature infants in neonatal intensive care units. We have observed an inhibitory effect by this vitamin E preparation on the in vitro response of human lymphocytes to phytohemagglutinin (PHA). E-Ferol suppressed the expected response to low doses of PHA. However, this suppression was not due to the alpha-tocopherol acetate (vitamin E) component, because alpha-tocopherol acetate by itself was not inhibitory; in fact, it often enhanced the PHA response. Because a mixture of polysorbate 80 and polysorbate 20 is used as a carrier in E-Ferol, these components were also tested and were found to be responsible for the suppression, especially the polysorbate 80. Concurrent with this suppression of PHA-induced mitogenesis was a decrease in the percentage of T11 lymphocytes.

Humans↗
PubMed1982

Elevation of natural killer activity and nonspecific immunity following injection of Listeria cell walls.

Mice given a single intraperitoneal injection of cell walls from Listeria monocytogenes (LCW) prior to challenge with Candida albicans or a mammary carcinoma showed significantly increased survival compared to saline injected controls. The cell walls were mitogenic for spleen cells in vitro. Levels of stimulation were lower than for Con A and PHA but comparable to those induced by LPS. Peritoneal exudative cells, but not spleen cells, harvested from mice injected with LCW showed significant elevation of natural killer (NK) cell activity as early as 1 day following injection. NK activity remained elevated for 10 days and then returned to normal levels by day 145. Macrophage phagocytic and tumorcidal activity in vitro did not appear stimulated. In overall comparison to commercial mitogens, LCW had lower levels of activity measured in vitro but equivalent or higher in vivo levels of protection.

Animals↗
PubMed1980

Determination of bioavailability of some long-chain N-substituted derivatives of L-methionine and L-lysine.

The bioavailability of N-acyl-L-methionine derivatives has been determined using microbiological assay with Tetrahymena pyriformis. It was found that palmitoyl- and stearoyl-L-methionine, stearoyl-L-methionine ethyl ester, and stearoyl-L-methionine sodium salt were partially utilized (14-38%) for growth of the microorganism. These compounds partially inhibited utilization of free methionine added to the media. The shorter derivatives, acetyl-, hexanoyl-, lauroyl-, and myristoyl-L-methionine completely inhibited the growth of T. pyriformis. This effect was not reversed when DL-methionine was added to the media. N6-fatty acyl L-lysine derivatives gave low availability values (3-18%) in microbiological assessment with T. pyriformis. N2-Acetyl-and N6-acetyl-lysine did not inhibit the utilization of the added parent amino acid. Nutritional evaluation of L-methionine derivatives by the rat growth method using net protein ratio (NPR) as the performance index indicated complete availability of stearoyl-L-methionine, stearoyl-L-methionine sodium salt, and partial availability of stearoyl-L-methionine ethyl ester (52%), stearoyl-L-methionylglycine (32%), and lauroyl-L-methionine (75%).

Animals↗
PubMed1978

Mitogenic and protective activity associated with a lipopolysaccharide from Coxiella burnetii.

A purified lipopolysaccharide (LPS) isolated from the rickettsial agent of Q fever, Coxiella burnetii phase 1, possesses some of the in vivo and in vitro biological properties previously only associated with bacterial endotoxins. The Coxiella LPS is mitogenic for guinea pig leukocytes, induces non-specific resistance in mice to virulent Candida albicans, causes dermal Schwartzman reactions, and is positive by the limulus lysate assay.

Animals↗